두경부 방사선 치료 환자에서 투과선량 알고리즘의 임상 적용시 불균질 조직 보정에 관한 연구 = Tissue Inhomogeneity Correction in Clinical Application of Transmission Dosimetry to Head and Neck Cancer Radiation Treatment

국문 초록 (Abstract)

목 적: 두경부에 방사선 치료를 받는 환자에서 투과선량측정시스템을 적용하여 시스템의 재현성과 선량 계산 알
고리즘의 정확도를 확인하기 위하여 본 연구를 시행하였다. 대상 및 방법: 2001년 9월 5일부터 9월 18일까지 4 MV 선형가속기를 이용하여 두경부에 방사선치료를 시행한 환자를 대상으로 하였으며, 3회 이상의 측정을 시행하고 조사야의 중심이 차폐되지 않은 35명의 환자를 대상으로 분석을 시행하였다. 매일 환자의 치료 시작 전과 치료 중 한 시간 간격으로 10×10 cm2 개방 조사야에 100 MU을 조사하고 측정을 시행하여 시스템의 안정성 및 재현성을 확인하였다. 투과선량 계산 알고리즘의 정확도를 평가하기 위하여 두경부 방사선치료 환자에서 투과선량의 예상치를 구하고 측정치와 비교하였다. 투과선량 예상치는 환자의 CT 또는 MR 영상과 모의치료 시의 X-선 필름을 사용하여 방사선 투과 부위의 골조직, 공기, 지방조직의 두께를 측정하고 이에 대한 불균질 조직의 영향을 보정하였다. 결 과: 10×10 cm2 개방 조사야에 100 MU을 조사하여 측정을 시행하였을 때 측정치의 일 중의 오차가 ±0.5% 이내이고 일간의 오차가 ±1.0% 이내로 시스템의 안정성 및 재현성을 확인할 수 있었다. 투과선량 예상치와 실제 측정치 간의 평균 오차는 뇌 부위 치료 환자에서는 ±5% 이하, 두부 치료 환자에서는 ±2.5% 이하, 경부 치료 환자에서는 ±5% 이하이었다. 결 론: 투과선량측정시스템의 안정성과 재현성을 확인할 수 있었고, 외부 형태가 불규칙하고 불균질 조직이 포함되는 부위에 대하여 CT, MR 등의 영상을 이용하여 불균질 조직에 대한 보정을 함으로써 정확한 예상치를 구할 수 있음을 확인하였다.

다국어 초록 (Multilingual Abstract)

Purpose: To confirm the reproducibility of in vivo transmission dosimetry system and the accuracy of the
algorithms for the estimation of transmission dose in head and neck radiation therapy patients.
Materials and Methods: From September 5 to 18, 2001, transmission dose measurements were performed
when radiotherapy was given to brain or head and neck cancer patients. The data of 35 patients who were
treated more than three times and whose central axis of the beam was not blocked were analyzed in this
study. To confirm the reproducibility of this system, transmission dose was measured before daily treatment and
then repetitively every hour during the treatment time, with a field size of 10×10 cm2 and a delivery of 100 MU.
The accuracy of the transmission dose calculation algorithms was confirmed by comparing estimated dose with
measured dose. To accurately estimate transmission dose, tissue inhomogeneity correction was done.
Results: The measurement variations during a day were within ±0.5% and the daily variations in the checked
period were within ±1.0%, which were acceptable for system reproducibility. The mean errors between
estimated and measured doses were within ±5.0% in patients treated to the brain, ±2.5% in head, and ±
5.0% in neck.
Conclusion: The results of this study confirmed the reproducibility of our system and its usefulness and
accuracy for daily treatment. We also found that tissue inhomogeneity correction was necessary for the
accurate estimation of transmission dose in patients treated to the head and neck.

목차 (Table of Contents)

• 서 론
• 연구 대상 및 방법
• 연구결과
• 고찰 및 결론

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